Enhancing Electromagnetic Backscattering Responses for Target Detection in the Near Zone of Near-Field-Focused Phased Array Antennas

The analysis of electromagnetic (EM) scattering from a target located in the near zone of an electrically large near-field-focused (NFF) array of antennas is presented. The analysis first examined the EM scattering from a metal sphere, attempting to create a reference for comparison with other targets in a fashion analogous to conventional far-field analysis of radar cross section (RCS). Realistic targets were afterward examined and analyzed to exhibit their RCS characteristics. A numerical simulation-based maximization of EM scattering fields for effective target detection in the near zone of antenna was developed, which allows one to obtain a set of optimum element excitation weightings by applying the steepest ascent method (SAM). RCS phenomena were validated by full-wave simulations and experimental measurements to justify the feasibility of the proposed concept.